1988 Jeep Wrangler Wiring Harness Install - Feelin' Burned

There comes a time in any venerable old Jeep's life when a certain part reaches its mechanical limits. That time when the part screams "Enough is enough!" For our '88 Wrangler, there are more than a few parts that are near or have exceeded their mechanical limits. You know this, we know this, heck, the engineers who designed this thing also know this. We have spent countless hours forcing love upon this hateful Jeep, trying as we might to replace parts that are worn out, broken, or were just cobbled together. We've done most of this within the pages of Jp fixing this and fixing that; it never seems to end.

Many will remember the image of smoke pouring out from under the hood of this first-generation Jeep Wrangler. That smoke came from the burning of insulation from part of the factory wiring harness cause of a short. Somehow we were able to put the fire out, pull a few singed wires and a relay, and for some reason the Jeep still functioned remarkably well, allowing us to squeak it through Arizona emissions and even an ill-advised wheeling trip or two. Fast forward a few months and no one will deny that the wiring in our YJ, fondly (or hatefully) known as Number Two, must be replaced. Years of neglect, multiple insufficient splices, and other dubious wiring repairs—along with drying of insulation and rusting of wires—have left the entire harness as a major liability.

Luckily for us and this spiteful evil vehicle, Painless Performance Products has a nearly plug-and-play wiring harness for this and all YJ Wranglers. That should make our life a bit easier and bring new life to our old YJ. Also, this new wiring harness is in much better shape than the 25-year old harness our Jeep rolled off of the factory line with—even 25 years ago. How, you may ask? Well, Painless has done its homework and updated the harness for these Jeeps over the past several years. Count that as a win for us. We also installed some of Painless Performance's new Classic Braid to keep the new harness looking beautiful while adding protection. Pretty soon ol' Number Two is gonna be so nice that we'll have to start calling it Number One. Follow along as we take this old Jeep through yet another repair and upgrade. Also, check out a few tips we have that will make any wiring repair you may undertake more successful.

Step By Step

The first step in installing Painless Performance’s YJ replacement harness (PN 10111, $899.99) is getting the old harness out of the way. The temptation is to grab as many wires as you can and yank them out with impunity, but in reality you are much better off taking your time carefully removing the old harness. Several of the plastic plugs are no longer made, so you end up having to reuse parts of the factory harness. Also, taking the old harness out helps you learn where the wires of the new harness will need to be routed.

If you do choose to solder your wires together, here is a tip from our pal, Mike, who has worked in the computer industry for decades. First, put a piece of shrink wrap over the longest wire you want to solder to keep it away from the heat. Then strip the two wires and bend them into an L-shape about 3⁄8- to 1⁄2-inch from the end. Then place them over one another and twist them so that the bottom of the L from one wire is wrapped around the top of the L from the other wire. Then solder and apply the heat shrink. Mike also recommends using the smallest-diameter rosin cored silver soldering wire you can get from Radio Shack.

Painless Performance’s Classic Braid Chassis Kit (PN 70970, $270) comes with plenty of black Classic Braid that looks like some factory wire loom. The braid can resist 300 degrees Fahrenheit and only melts at 475 degrees. The Chassis Kit comes with enough braid to do at least a few Jeeps and also includes zip ties, heat shrink, and a couple of roles of self-vulcanizing tape for those junctures where some wires go one way and others go another.

If you’ve been reading Jp for a little while, then you know that the harness in this ’88 YJ has been on fire. Honestly, at that point we were so mad at the Jeep that if it would have continued to burn we would have stepped back and watched. Muhaaa haa haa! But the small fire went out. While removing the old harness, it became very clear that that fire was not an isolated event. There were many spots in the old harness that were basically fires waiting to happen.

Installation of the new harness is pretty simple, but it is worth it to take your time routing wires. Conveniently, there are several tags on the Painless harness that indicate what a group of wires do. Each wire is individually printed with information about what it does and where it goes. All wires are also color coded to add to the ease of installation.

Last tip we can give you is to make sure that all the ground wires are hooked up and provide a good ground. Here we cleaned off the paint to be sure that the ground is solid. Also, the wiring harness comes with a couple of braided ground straps to run from the battery to the engine, battery to chassis, and chassis to body. Intermittent or bad grounds are tough to diagnose and can ruin a fun day quickly.

So we mentioned that some of the plastic plugs from the old harness have to be reused. The very detailed instructions that come with the harness tell you when you need to reuse a connector. The Painless Performance harness has crimp-connectors in place when a factory plug has to be reused. If you are like us, you can alternatively solder these joints and cover the joints with heat shrink. Here is one of the plastic connectors that must be reused if you want to retain the factory YJ dash-lights. Other parts just clip together with a snap in the factory location using new plastic plugs.